1. Field of the Invention
The present invention relates to a driving method and related device of an LCD, and more particularly, to a driving method and related device for reducing power consumption and electromagnetic interference of the LCD.
2. Description of the Prior Art
Featuring low radiation, thin appearance and low power consumption, liquid crystal display (LCD) devices have gradually replaced traditional cathode ray tube (CRT) displays and are widely used in information products such as notebook computers, personal digital assistants (PDA), flat panel televisions and mobile phones.
Generally, a driving system of the LCD device is formed by a timing controller, a data-line driving circuit and a scan-line driving circuit. The timing controller is utilized for generating driving data of the LCD device according to image data being received, as well as timing signals and control signals required for operating the LCD device. The data-line driving circuit and the scan-line driving circuit are utilized for performing logic operations on the driving data, the timing signals and the control signals to generate driving signals of data-lines and scan-lines, respectively.
The timing signals generated by the timing controller may include a horizontal clock signal (CPH) and a vertical clock signal (CPV), for example, while the control signals may include a horizontal start signal (STH), a vertical start signal (STV), a data load signal (LD), a polarity control signal (POL) and an output enable signal (OE), all of which are well-known by those skilled in the art and not narrated herein. In addition, the data-line driving circuit and the scan-line driving circuit may further include multiple source drivers and multiple gate drivers. Each of the source drivers (or the gate drivers) is utilized for driving multiple data-lines (or multiple scan-lines), and required quantities of the source drivers and the gate drivers are determined by resolution of the LCD device.
In the prior art, the data-line driving circuit usually takes the scan-line as a basic unit to output the data-line driving signals of a same scan-line sequentially line-by-line, so as to drive the LCD panel for displaying an image. In this case, the data-line driving circuit has to read in the driving data outputted by the timing controller successively to generate the data-line driving signals according to the control signals and the clock signals.
Please refer to FIG. 1. FIG. 1 shows a timing diagram of a conventional LCD device, in which T_DATA stands for the driving data outputted by the timing controller, CPH stands for the horizontal clock signal, STH stands for the horizontal start signal, LD stands for the data load signal, POL stands for the polarity control signal, and LINE_n stands for the data-line driving signal corresponding to one data-line in the LCD device. The horizontal clock signal CPH provides a reference clock for operating the data-line driving circuit; the horizontal start signal STH triggers the data-line driving circuit to receive the driving data outputted by the timing controller; the data load signal LD controls output operation of the data-line driving circuit; and the polarity control signal POL controls polarity of the data-line driving signal outputted by the data-line driving circuit. In addition, for the purpose of convenience, the driving data T_DATA outputted by the timing controller is shown by blocks. Each block represents driving data corresponding to a same scan-line, and blank space represents a blanking signal for separating the adjacent driving data.
From the standpoint of the (N−1)th scan-line, the horizontal start signal STH corresponding to the (N−1)th scan-line is firstly generated to control the data-line driving circuit to receive a corresponding driving data block. Then, the data-line driving circuit is controlled to output a data-line driving signal and convert the polarity of the data-line driving signal by the data load signal LD and the polarity control signal POL corresponding to the (N−1)th scan-line, respectively. Similarly, such operation is repeated for the Nth and the (N+1)th scan-line as well.
In the prior art, when two image data successively received by the timing controller, such as image data corresponding to the (N−1)th and the Nth scan-line, are the same, the driving data, the clock signal and the control signal still have to be generated repeatedly for driving the (N−1)th and the Nth scan-line according to the two identical image data being received. However, this causes unnecessary power consumption of the LCD device. Additionally, with the increase in resolution of the LCD device, redundant signal transmission may also result in a severe electromagnetic interference (EMI) problem.